Various types of ion generator or ionizer, for generating air ions by corona discharging and for neutralizing static electricity on an object with air flow including the air ions by means of a fan, have been developed. Such a type of ionizer has an electrode needle (or a discharging needle) for generating corona discharging. The discharging performance of the electrode needle may be deteriorated, after use, when dust in the air is adsorbed on the tip of the needle. Therefore, it is necessary to clean the electrode needle periodically. For example, Japanese Unexamined Patent Publication (Kokai) No. 2004-234972 discloses an air-flow type ionizer and describes that “a fin portion receives an air flow and a movable member is activated. Then, a brush member attached to the movable member comes into contact with the tip of a discharging needle, whereby the dust adsorbed on the tip of the needle is removed”. Also, Japanese Unexamined Patent Publication (Kokai) No. 2004-234972 describes that “a cleaning means may be configured to be activated by an electric motor”.
On the other hand, U.S. Patent Publication No. 5,768,087 discloses “a cleaning device for automatically cleaning dust and dirt from ionizing electrodes”, and describes that “The cleaning device generally comprises a brush assembly, a weighted portion and a restoring mechanism”. In addition, an air ionizer (Model Number: BF-27C), having a brush for cleaning an electrode needle and a photoelectric tube for detecting the position of the brush, is commercially available from SHISHIDO Electrostatic Ltd.